Electrical installation comprising a decompression channel

ABSTRACT

The invention relates to an electrical installation, especially a medium-voltage switchgear, comprising at least one encapsulated function module (FM), a decompression channel (DK) which is connected to said function module, and at least one inflow opening (EO . . . ) which connects the function module (FM) to the decompression channel (DK). The covering surface (DF  1,2,3 ) of the decompression channel (DK), opposite the inflow opening (EO . . . ), comprises at least one partial region which is obliquely oriented in relation to the inflow direction. Hot gases and high pressures produced during an accidental arc can thus be evacuated from the installation, without any risk to humans and buildings. Pressure channels are used, inter alia, in installations used in relation to medium-voltage technique for providing and distributing energy.

CLAIM FOR PRIORITY

This application is a national stage application of PCT/DE02/00933,which was published on Mar. 11, 2002, which claims the benefit ofpriority to German Application No. 10114742.2, filed Mar. 20, 2001.

TECHNICAL FIELD OF THE INVENTION

The invention relates to an electrical installation, and in particularto a medium-voltage switchgear assembly.

BACKGROUND OF THE INVENTION

For the protection of persons and of the installation, medium-voltageswitchgear assemblies are provided with apparatuses for releasingpressure in order for it to be possible for the hot gases produced inthe event of an arc flashover to be dissipated safety from theinstallation area. A number of functional modules are usually used forthese switchgear assemblies, the functional modules being encapsulatedwith respect to one another and with respect to the atmosphere such thatthe effects of an explosion in the interior of the functional modulecannot spread to the area surrounding the installation. In the event ofan arc forming in one of these functional modules, the excess pressureproduced by the air suddenly being heated and the hot gases aredissipated such that neither persons nor the installation are harmed ordamaged in any way. Pressure release ducts are usually provided for thispurpose and are connected to the individual functional modules by meansof a suitable valve system such that it is possible for the excesspressure and the hot gases to be dissipated from the affected functionalmodule but at the same time such that it is not possible for the hotgases or a pressure wave to enter the other functional modules.

DE 31 25 364 A1 describes a pressure release duct which is rectangularin cross section and in whose interior the hot gases are first cooled byswirling and the excess pressure is reduced. Then, the gases aredissipated from the installation via ventilation slots such that theyare thereafter only slightly harmful.

In DE 195 20 698 A1 and DE 196 45 304 C1, the pressure and temperatureare reduced using so-called damping elements, in the form of cartridges,which are installed either within the installation or externally. Thegases are in this case directed away either via ventilation slots intothe area of the building surrounding the installation or to the outsidevia a chimney system.

With all of these solutions it is possible, however, for the pressurerelease duct having a rectangular cross section not to be suitable forloads in the case of particularly intensive arc flashovers.

SUMMARY OF THE INVENTION

The invention discloses dissipation of the high pressures andtemperatures which occur during an arc discharge without posing a riskto persons and the installation, and to ensuring sufficient robustnesseven for the case of intensive arc discharges and their effects.

In one embodiment of the invention, the top surface, which is oppositethe inflow opening, of the pressure release duct has at least onesubarea which is aligned obliquely with respect to the inflow direction.Obliquely is understood here to mean any deviation from a right angle incomparison to the flow direction, which results in the gas not beingreflected exactly straight.

The advantages achieved by the invention are, firstly, that thecross-sectional form described has greater static robustness than therectangular cross-sectional form since the cross-sectional formdescribed can be as close as desired to a round cross-sectional formwhich is optimum for robustness. Optimum robustness is achieved by thecross section having as few straight surface areas as possible which canbe susceptible to bending. Secondly, the advantage of the designaccording to the invention is that the pressure wave entering thepressure release duct through the inlet opening is scattered on thecover surface which is opposite the inlet opening by being reflected indifferent directions. In this manner, extreme pressure peaks can largelybe ruled out by superimposing other pressure waves on them.

One advantageous embodiment of the invention provides for the pressurerelease duct to have a trapezoidal cross-sectional profile. Therefinement in which the cross-sectional surface has a trapezoidal formfirstly provides great robustness and, secondly, makes simplemanufacture possible.

A further advantageous embodiment of the invention provides for thepressure release duct to have sloped end regions. By this means, thepressure wave which propagates in the longitudinal direction of thepressure release duct is scattered and the pressure peaks are leveledoff.

A further advantageous embodiment of the invention is that the topsurface of the pressure release duct has at least one sloping surfaceapproximately opposite the inflow opening in the inflow direction.

In this manner, the pressure wave entering the pressure release ductthrough the inflow opening can be dispersed and thus weakened right atthe start.

A further advantageous embodiment of the invention provides for thepressure release duct to have a pressure release opening to the exteriorof the installation. The pressure wave and the gases produced are inthis case either dissipated into a pressure- and temperature-resistantarea, in which there are no people, or are directed outside via achimney system. In this manner, reliable dissipation is ensured withoutposing any risk to the installation or people.

A further advantageous embodiment of the invention is for the pressurerelease duct to be connected to the exterior of the installation via anabsorption element. The absorption element reduces both the temperatureand the pressure to such an extent that the gases can be dissipated bothinto a pressure- and temperature-resistant area or via a chimney systemto the outside and into the area directly surrounding the installation.

A further advantageous embodiment of the installation provides for thepressure release duct to have ventilation openings on its top surfacewhich close in a pressure-tight manner in the event of a pressure surgeoccurring in the pressure release duct. This ensures that sufficientcooling air is dissipated from the installation for normal operation ofthe installation. In the event of an arc flashover with the occurrenceof hot gases and high pressures, the ventilation openings are closed bymeans of valves and prevent the gases from escaping into the areasurrounding the installation.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is explained in more detail by exemplary embodimentsdepicted in the figures. The invention is described in more detailbelow.

In the drawings,

FIG. 1 shows a view of the cross section through a functional modulewith a pressure release duct having a trapezoidal cross section placedon top.

FIG. 2 shows a view of a plurality of adjoining functional moduleshaving a common pressure release duct.

FIG. 3 shows a view of the cross section through a pressure release ducthaving a trapezoidal cross section.

DETAILED DESCRIPTION OF THE INVENTION

The functional module FM shown in FIG. 1 is divided up into a pluralityof functional compartments FR 1, 2, 3. These compartments are separatedfrom one another in a gas-permeable manner by partition walls SW 13, 23.In other designs, the partition walls SW . . . can also separate theindividual functional compartments FR . . . from one another in apressure-tight manner. The individual functional compartments FR . . .may be, for example, switching module compartments FR 1 having powerbreakers LS, connection compartments FR 3 or busbar compartments FR 2.The outer walls AW of the functional module FM shown are closed off in apressure-tight manner both from the area surrounding the installationand from any further functional modules FM . . . which may be adjacent.In the exemplary embodiment shown, the inlet openings EO 1, 2, 3 to thepressure release duct DK are on the top face of the functional moduleFM. In this case, each functional compartment FR 1, 2, 3 has its ownconnection to the pressure release duct DK such that a fault in one ofthe functional compartments FR 1, 2, 3 does not have any effect on theother functional compartments FR 1, 2, 3. The inlet openings EO 1, 2, 3to the pressure release duct DK are closed in the exemplary embodimentshown by valve systems KS 1, 2, 3 having a non-return valve functionsuch that gas can only flow from the functional module FM, and not fromthe pressure release duct DK into the functional module FM.

FIG. 2 shows, schematically and in longitudinal section, a plurality ofadjoining functional modules FM, FM . . . having a common pressurerelease duct DK in the longitudinal direction. If an arc flashover nowoccurs in a functional module FM, the air in this functional module FMis supplied with a large amount of heat causing it to expandexplosively. The pressure wave produced can then be dissipated via thevalve system KS 1, 2, 3 (in FIG. 1) into the pressure release duct DKbut cannot spread to other functional modules FM . . . owing to thenon-return valve function of the valve system KS 1, 2, 3. On the topsurfaces DF 1, 2, 3 (in FIG. 3) opposite the inlet openings EO . . . inthe pressure release duct DK, the pressure wave is scattered in morethan one direction and the maximum pressure is thus reduced. Thisprocess takes place more than once while the pressure wave spreads inthe longitudinal direction of the pressure duct DK, with the result thatthe pressure peak can be safely reduced. In addition, surfaces slopingFS 1, 2, 3 are shown in the longitudinal direction above the inflowopenings EO . . . , provided on each individual functional module FM, FM. . . , and on the end regions EB1, 2 of the pressure release duct DK,and these surfaces cause the pressure wave to be scattered further, andthus cause the pressure peaks to be reduced. The swirling of the gasesin the pressure release duct DK causes both the pressure and thetemperature to be reduced dramatically. In order to finally dissipatethe gases, the pressure release duct DK can be connected to a chimneysystem KM or coupled to an absorption element AE, with the pressure andthe temperature being reduced to such an extent that the gases can besafely dissipated onto the area surrounding the installation. Absorptionelements AE usually comprise chambers filled with a filling material,for example metal chips, in which the gases are heavily scattered,swirled, cooled and neutralized. The dissipation of heat takes placethrough heat conduction and possibly also melting processes of thefilling material. Instead of the loose filling material, metal sheetswhich are arranged offset in relation to one another may also be used tocool and swirl the flow, with it also being possible for the metalsheets to have distributed openings. Furthermore, the arrows are alsoindicated a possible course for the flow of gas GS in the pressurerelease duct DK. In particular, the swirling areas can be seen on thesloping surfaces FS 2, 3.

FIG. 3 shows an enlarged illustration of the pressure release duct DKhaving a trapezoidal cross section as an exemplary embodiment of theinvention. In addition to trapezoidal cross sections, for example crosssections in the form of semi-circles or other polygonal forms may alsobe provided according to the invention.

The inlet openings EO . . . having the valve systems KS can be seen.These are, for example, loose valves on the inlet openings EO . . . ,which are opened by the pressure wave, thus allowing the flow of gas GSinto the pressure release duct DK. Some of the inlet openings EO . . .are opposite sloping cover surfaces DF 1, 2, 3, which reflect theincoming hot gases in different directions and thus dissipate them sothat the pressure peaks can be reduced. A course for the flow directionsSR of the gas which is possible owing to the swirling is depicted. Alsoshown are the ventilation openings LO 1, 2 which are provided on thecover surface DF 1, 2, 3 of the pressure release duct DK and are closedin a pressure-tight manner by means of the valve system KS . . . in theevent of a pressure surge in the pressure release duct DK.

1. An electrical installation, in particular a medium voltage switchgearassembly comprising: at least one encapsulated functional module and apressure release duct connected thereto; at least one inflow openingwhich connects the functional module to the pressure release duct, a topsurface, which is opposite the inflow opening, of the pressure releaseduct having at least one subarea which is aligned obliquely with respectto the inflow direction, wherein the pressure release duct hasventilation openings on the top surface, which close in a pressure-tightmanner in an event of a pressure surge occurring in the pressure releaseduct.
 2. The electrical installation as claimed in claim 1, wherein thepressure release duct has a trapezoidal cross-sectional profile.
 3. Theelectrical installation as claimed in claim 1, wherein the pressurerelease duct has sloping end regions.
 4. The electrical installation asclaimed in claim 1, wherein the top surface of the pressure release ducthas at least one sloping surface approximately opposite the inflowopening in the inflow direction.
 5. The electrical installation asclaimed in claim 1, wherein the pressure release duct has a pressurerelease opening to an exterior of the installation.
 6. The electricalinstallation as claimed in claim 1, wherein the pressure release duct isconnected to the exterior of the installation via an absorption element.